This invention relates to a guide bar for a chainsaw for guiding a continuous loop of saw chain around the working end tip and back to the power unit to which it is mounted. More particularly, the invention relates to a chainsaw guide bar that is especially configured and adapted for executing fine details in an artistically carved wooden or similar workpiece via an improved guide bar of greatly reduced weight and structure in contrast to conventional commercially available guide bars. The invention therefore relates to a guide bar that is intended to be used for, and excels in, non-conventional artistic carving purposes, such as curvilinear carving and shaping with sharp radiused cuts, with great ease and efficiency.
Chainsaws have been used in the logging, lumber and wood processing industry for nearly 100 years. Chainsaws and their component parts have been designed to withstand the rigors of this industry. Resulting guide bar design has remained relatively bulky and heavy in nature to meet industry demands.
Since a chainsaw guide bar can comprise up to 25% of a chainsaw's weight, a reduction in guide bar weight can significantly reduce the overall weight of a chainsaw. Furthermore, since the guide bar extends some distance forward of the users hands, its weight is leveraged and over time produces a very tiring effect on the user. This tiring effect can increase the risk of accident and injury as well as reduce the amount of time a user can operate a saw.
In the past, several methods have been devised to lighten the chainsaw bar. All of them have utilized either a method of replacing areas of the solid body of the bar with inserts of a lighter weight material or by leaving hollow areas in the center plate or plane of a laminated bar or by making the width of the bar thinner or a combination of these methods. Chainsaw guide bars to this point in time have been fully planar along their working end, without any hollows or holes of any significant size.
One previously granted patent, U.S. Pat. No. 2,660,204 [Rosenboom] describes an adjustable chain saw bar that has a chain guiding track that is adjustable in width so that the working clearance can be easily maintained, cuts straight, and adds strength and rigidity to the bar. The drawbacks of this design are that it will not cut in a curved fashion. Further this type of chainsaw bar is not lightweight. Additionally, this guide bar cannot be used for non-conventional purposes, such as carving and shaping.
Another prior patent, U.S. Pat. No. 4,138,813 [Harada] describes a chain saw guide bar which is light weight and includes a pair of plates of small thickness each formed on the surface of the guide bar and forms a groove on each of their surfaces to increase the rigidity and strength of the guide bar. The drawbacks of this design are that it is a fully planar design, with no hollows or holes to lighten the chainsaw bar. Additionally, it is not capable of sculpting, carving, shaping or executing precise cutting of a small amount of wood or similar material such as ice, stone, composite material, bone, and food stuffs.
Another earlier apparatus is described in U.S. Pat. No. 4,654,972 [Sellmaier] as an elongate chain support blade that provides clearance between respective runs of the chain and longitudinal edges of the blade, thereby reducing friction and reducing oil usage. The drawbacks of this design are that it is not lightweight; and it does not contain any hollows or holes to lighten the chainsaw. Additionally, it contains a spur wheel and guide wheel at the front end of the blade. Moreover, it is designed for the purpose of cutting trees and not capable of sculpting, carving, shaping or executing precise cutting of a small amount of material.
Still several earlier devices describe chain saw guides which have cut-out sections filled with resin or some other non-metallic material to reduce the weight of the guide bar while still retaining rigidity. U.S. Pat. No. 4,837,934 [Krohn] describes a chain saw bar that defines an elongate open area within which is formed an insert member of a lightweight, non-metallic material. U.S. Pat. No. 5,014,435 [Date] describes a chain saw guide with an inner plate and a pair of outer plates fixed to the two flat sides of the inner plate. The inner and outer plates have holes that are filled with resin in order to lighten the weight of the saw but still maintain the rigidity. U.S. Pat. No. 5,025,561 [Sugihara] describes a guide bar for a chain saw with holes in the main body which contains a resin filler which would be shock-absorbing, weight-lightening in order to give rigidity to the guide bar and also cut down on vibrations. Finally, U.S. Pat. No. 5,035,058 [Date] describes a chain saw guide bar having oppositely located flat sides, with a plurality of recesses on each side and some recesses being filled with a lightweight material, while others function as oil reservoirs and oil passages between the guide grooves of the bar.
The drawbacks to these designs are the inserts or holes are filled with a non-metallic or resin material which are used solely for the purpose of stiffening and adding rigidity to the bar. Additionally, it is designed for users in the logging industry, so they are much larger than the present invention. Moreover, the guide bar is planar, and used for cutting in a straight line, and not capable of allowing for carving and sculpting small amounts of material.
Still other prior patents describe planar guide bars that contain longitudinal extending cutouts that are filled with a lighter weight material. U.S. Pat. No. 5,271,157 [Wieninger] describes a guide bar with two steel side parts and a center part connected to the side parts. Additionally, the guide bar contains cut outs in the side parts and in the center part of the guide bar extending in the longitudinal direction which are filled with a lighter material. U.S. Pat. No. 5,842,279 [Andress] describes a guide bar with a single steel plate, and a cut out extending over a portion of the longitudinal extension and over a portion of the height filled in with a casting material having a smaller density than the steel plate. The casting material is used for the purpose of adding a high torsional stiffness and lightening the weight of the guide bar. U.S. Pat. No. 6,427,342 [Breitbarth] describes a guide bar for a chain saw having an elongate planar body with an opening extending therethrough, and an elongate insert made from a lighter weight material to fit within the opening in the main body.
The drawbacks of these designs are that the guide bars have a great length and are more difficult to handle. Additionally, the guide bars are all planar. They all contain at least one main elongated cutout in the center of the guide bar, which then needs to be filled with a lighter weight material in order to add rigidity to the guide bar, so that it will cut steadily in a straight line. They are not capable of cutting in a curved manner. Moreover, these devices are made for larger scale industrial use. Additionally, it would not be capable of carving or sculpting small amounts of material.
In recent years, the appearance of alternate cutting applications has increased, due to the chainsaws continuing decrease in weight These alternate uses require more precise cutting of less material than traditionally required by a chain saw, thus, the guide bar strength is less of an important factor of its usefulness as is its reduction in weight. These alternate uses also require the freeform shaping of wood or similar material whereas the new bar designs ability to make curved cuts rather than straight cuts would greatly increase its usefulness as well as its maneuverability and ease of manipulation. These alternate uses include but are not limited to ornamental and architectural shaping as well as for furniture and sign making, timber frame and log construction applications and chain saw art and crafts.
Operating a chainsaw, for a purpose such as carving a statue or figure from wood is an extremely physically tiresome task. Not only does the chainsaw need to be supported in an infinite number of physical positions, but also constantly and forcefully manipulated in both random and repetitious manners. Since there is such a great deal of guide bar manipulation in the process of shaping wood or material, heavy guide bars are extremely cumbersome and wearing on the user, increasing risk of accident or injury and decreasing the carvers quality of workmanship as well as the time a carver can safely operate the chainsaw.
The carving and shaping of wood or other material often requires the shaping of concave and convex surfaces. Modern, standard chainsaw guide bars are designed to cut in a straight line. Obtaining such shapes with a guide bar that cuts straight is a tedious process. Narrow tipped guide bars are available and marketed to the carving industry; however, they are fully planar in design, restrictive to making radius and curved cuts and heavy, as they are constructed in the same manner as a guide bar designed for felling trees and sectioning logs.